Fixes for Classic 1.15.9

[umuppetu]

Classic 1.15.9 appears to have adopted more of Retail's namespaced AddOn API. GetAddOnMetadata is no longer available as a global, so this line explodes during addon initialization. This is exactly the same class of breakage that happened on Retail in 11.0 when Blizzard moved APIs into C_AddOns

[b4bass]

Message: Interface/AddOns/ItemRack/Libs/Libs.xml:3 Error loading Interface/AddOns/ItemRack/LibStub/LibStub.lua
Message: Interface/AddOns/ItemRack/Libs/Libs.xml:4 Couldn't open Interface/AddOns/ItemRack/CallbackHandler-1.0/CallbackHandler-1.0.xml
Message: Interface/AddOns/ItemRack/Libs/Libs.xml:5 Error loading Interface/AddOns/ItemRack/LibDataBroker-1.1/LibDataBroker-1.1.lua
Message: Interface/AddOns/ItemRack/Libs/Libs.xml:6 Error loading Interface/AddOns/ItemRack/LibDBIcon-1.0/LibDBIcon-1.0.lua

and when i try to open the interface, i get
otherwise addon seems to work fine

Message: Interface/AddOns/ItemRack/ItemRack.lua:1944: attempt to call a nil value
Time: Wed Jul 22 19:08:28 2026
Count: 1
Stack:
[C]: in function 'EnableAddOn'
[Interface/AddOns/ItemRack/ItemRack.lua]:1944: in function 'ToggleOptions'
[Interface/AddOns/ItemRack/ItemRack.lua]:1926: in function 'OnClick'
[Interface/AddOns/DBM-Core/Libs/LibDBIcon-1.0/LibDBIcon-1.0.lua]:179: in function <...AddOns/DBM-Core/Libs/LibDBIcon-1.0/LibDBIcon-1.0.lua:177>

[Pimptasty]

Thanks for this — it's the right pattern and it fixes the load-time crash from #319.

Heads up that three call sites are still left on the removed globals, since Lua locals don't cross file boundaries and the ItemRack.lua alias here only covers GetAddOnMetadata:

• ItemRack/ItemRack.lua:1946-1947 — EnableAddOn / LoadAddOn in ItemRack.ToggleOptions
• ItemRack/ItemRackEvents.lua:280 — LoadAddOn in ItemRack.ToggleEvents

Both load the LoD ItemRackOptions, so with this PR applied the addon loads fine but opening the options panel or toggling events still throws attempt to call a nil value.

I've put the remainder up as #321, stacked on this branch rather than duplicating your work — it's branched from ffbb27a, so the intended merge order is #320 first, then #321, at which point #321's diff reduces to just the two extra commits.

Happy to close #321 if you'd prefer to just fold those three lines into this PR — your call, no attachment either way.